BSC 212 Exam 3

what is a fruit?

the matured ovary, often accompanied by accessory tissue which clings to the ovary when matured

what is a seed?

matured embryo, stored food, protective seed coat

what is embryogenesis?

formation of the embryo, establishes a body plan for the plant

how does the apical cell divide?

many times to become the embryo proper

what does the basal cell become?

the suspensor

what is the cotyledon?

embryonic leaf, first leaves to appear when seeds germinate

what does germination depend on?

water, oxygen, temp, light, seed coat rigidity, embryo dormancy by abscisic acid & gibberellic acid

what occurs during germination?

-primary root emerges
-epigeous or hypogeous stem emerges based on species

what is the epigeous stem?

cotyledons are carried out of the ground

what is the hypogenous stem?

cotyledons remain underground

what are breeding systems?

methods by which plant reproduce sexually

what are the 2 types of reproduction?

1) asexual
2) sexual

what is asexual reproduction?

vegetative (mitosis) the stolon & rhizomes

what is sexual reproduction?

alteration of meiosis & fertilization
-selfing
-outcrossing

what are the pros of asexual reproduction?

-reproduce quickly
-facilitate survival when difficult to find mates

what are the cons of asexual reproduction?

-deleterious genes do major damage
-genetically constrained

what are the pros of sexual reproduction?

-faster to obtain new favorable mutations (recombination during meiosis)
-novel genotypes: mating with populations & migration
-red queen hypothesis: host populations are continually evolving in response to pathogens
-avoiding mueller's ratchet: accumulation of deleterious mutation (via genetic recombination w/ natural selection)

what are the cons of sexual reproduction?

costly process

what are deleterious genes?

detrimental sequence of nucleotides forming the chromosome

what is a monoecious plant?

male & female organs on one plant (hermaphroditic)

what is a dioecious plant?

plants with male organs & plants with female organs

what is a gynodioecious plant?

plants with female organs & plants with male and female organs

what is a androdiecious plant?

plants with male organs & plants with male and female organs

what are the 3 drivers that affect the frequency of female plants in a population?

1) genetic drift: greater unpredictability in female frequency
2) nutrients in soil: more nutrients, more females
3) soil microbial community

what is chasmogamous?

open flowers

what is cleistogamous?

closed flowers, must self-pollinate

what is a protandrous plant?

male organs come to maturity before the female

what is a protogynous plant?

female organs come to maturity before the male

what is self-incompatibility?

inability to produce zygotes after self-pollination in a fertile hermaphrodite plant

how does SI work?

-sporophytic self incompatibility (SSI)
-gametophytic self-incompatibility (GSI): more common (60-90 families), less understood

what is gametophytic self-incompatibility (GSI)?

pollen exhibits incompatibility phenotype determined by its gametophytic genome (pollen): "like-matches-like inhibition"

what is sporophytic self-incompatibility?

pollen exhibits incompatibility phenotype of the sporophyte (diploid) parent (the female): "any-match-inhibition"

what are heteromorphic flowers?

perfect flowers with different structures

what is heterostyly?

different length relative to stamen in the flowers to reduce self-fertilization

what is distyly?

stamen & style 2 different heights

what is tristyley?

stamen & style 3 different heights

what is evolution?

change in characteristics of organisms over many generations

-takes place over generations, can be rapid

-changes must be hereditary

-selection is the mechanism of evolution

what are adaptations?

changes that better suit an organism to its environment

-arise from mutations selected on

-occur over generations, assimilations is change in individual

-NOT intentional

what is a species?

group that can interbreed but cannot with other groups
-speciation
-genetic isolation, restricts gene flow

what are mutations?

heritable changes in the genotype, most occur spontaneously

what is fitness?

viable offspring averaged over similar individuals & divided by average for all individuals in the population

what is the founder effect?

small population is separated & has a different gene pool than the parent

what is the bottleneck effect?

population is drastically reduced by an event (not selection) & the gene pool is disrupted

what is gene flow?

movement of alleles into or out of a population
-movement of gametes by pollen between pop.
-wind plants pollen falls around 50m

what does gene flow depend on?

proximity, wind patterns, pollinators, phenology

what is genetic drift?

change in gene pool due to chance

what can genetic drift lead to?

1) speciation: creation of a new species
2) inbreeding: breeding among closely related individuals

how is genetic drift calculated?

by measuring the effective population size (N left) or genetically unique individuals

what is inbreeding depression?

reduced fitness due to increased homozygosity; closely related individuals breeding

when is speciation & inbreeding more likely to happen?

when the gene pool is reduced, less variability (more similar genetically)

what is sympatric speciation?

polyploids (2+ sets of chromosomes), chromosomes do not separate during meiosis, diploid gametes created, diploid gametes combine

what is the result of sympatric speciation?

-hybrid cannot undergo meiosis because chromosomes cannot pair
-autopolyploidy double the chromosomes then after meiosis

what are bryophytes?

earliest land plants:
-liverworts
-mosses
-hornworts

what are ferns?

seedless vascular plants

what are gymnosperms?

plants that produce seeds without flowers:
-conifers
-cycads
-gingko
-gnetophytes

what are angiosperms?

plants that produce flowers as reproductive organs

what is paleobotany?

study of ancient plants with fossils

what does green algae have in common with vascular plants & bryophytes?

-contain chlorophylls a & b
-store starch inside plastids
-some have firm cell walls w/ cellulose, hemicellulose, pectin
-flagellated reproductive cells
-alternation of heteromorphic generations

what is the alternation of heteromorphic generations?

one generation is diploid (2n) & one generation is haploid (n)
key features:
-meiosis
-fertilization
-gametophyte (n)
-sporophyte (2n)
occurs in nonvascular plants

what are lichen (not plants)?

symbiotic partnership between fungus & alga:
fungus for decomposition, algae partner (green algae or cyanobacteria) for photosynthesis

mosses reproductive cycle:

1) spores released
2) spores germinate
3) gametophytes form
4) sperm to egg = zygote
5) zygote divides = sporophyte
6) venter forms calyptra
7) meiosis in capsule = haploid spores

what is heterospory?

production of 2 types of spores in 2 different sporangia

what does is mean to be homosporous?

meiosis produces only 1 kind of spore (many ferns)

what are oogamous plants?

vascular plants, nonmotile, large egg with sperm that swims to eggs
-sporophyte more complex than gametophyte

fern reproductive cycle:

1) spore made in the sporangia
2) spores dispersed
3) heart-shaped gametophytes with rhizoids
4) achegonia (F) & antheridia (M) sex organs on single gametophyte
5) sperm released by water fertilize neighboring egg
6) zygote to embryo to sporophyte

what is the dominant generation in the fern reproductive cycle?

sporophyte
(generations independent)

how do fern seeds disperse?

water

what are the limitations to spores in ferns?

megaspores released
limited nutrition available

what are the limitations to free-living gametophytes in ferns?

-genetically sensitive to mutations since 1N
-small limited support for embryo & young sporophyte

what is the best potential source for support (nutrition & protection) in ferns?

-need to have dimorphic spores
-retain megaspores
-retain female gametophytes
-sperm needs to be able to get to the ovule

when did farming practices arise?

10,000-1000 years ago
(neolithic revolution)

primitive agriculture:

-domestication of plants
-new tools & pottery
-plows: increased nutrient availability to plants
-manure as fertilizer
-harnessed animals

farming in the 1700s-1800s:

foundations of industrial ag:
-more machinery, still powered by animals
-steam engines
-mendel & plant genetics (1865)
-railroads (1869)
-first combine harvester (1884)
-beginning of seed businesses (1890s)

conventional farming: 1900s-current

-efforts to feed growing population
-haber-bosch process developed (1913)
-horses replaced with machines (tractors: 1915)

tracking farming trends of 1850-1940s:

-# of farms growing
-farm size relatively small, less than 200 acres

tracking farming trends of 1940s-current

-# of farms shrinking, fewer farms
-large-scale farms, now some 4.64 acres

1940-2000s farming:

-era of genetics, biochem, large scale farming
-industrialization: cheaper food, dependence on agrochemicals & fuel

21st century farming:

-advanced genomics & sustainability movement
-plant genome, new concepts for pests, computerized data, consideration of climate change

when did organic farming practices arise?

1930s-late 1940s: followed the Dust Bowl (1930-1940) & concerns for healthy soil

long-term agricultural studies:

-Rothemstead, England: (1843) to present for Ag studies
-The Park Grass experiment (1856): fertilizers affect on hay - longest ecological experiment in the world
-The Morrow Plots: (1876) for understanding crop rotation, soil nutrient depletion & fertilizers

what are some attributes for organic farming?

-sustainable considerations for farming (1900s) in response to observed damages due to pesticides/fertilizers
-no use of pesticides, herbicides, synthetic fertilizers
-no use of GMOs
-must protect their products for coming in contact with all of the above

what are some attributes for conventional farming?

-chemical intervention for pests (pesticides) & weeds (herbicides)
-providing fertilizers
-does not have to mean monocropping

what is food insecurity?

lack of available food and/or lack of resources to buy or barter for it
-800 mil (11%) of global pop in 2018
-US: 12.8% of households in 2022, 34 mil people

what are the risks to food insecurity?

-low wages
-unemployment
-insufficient social safety net for those w/ no or low income (single-parent families)
-living in rural area
-gov. & private industries that do not provide resources & aid to farmers
-lack of edu.
-environmental degradation